Ignition problem? won't start - sometimes...

[Five3Blazer]

http://youtu.be/TJjVnrhGGhQ

Heres a video of my problem. Most of the time it will start just fine but randomly it doesn't start normal and i have to let it sit a few minutes and keep trying to start it.

Ive looked around and seen it could be the BCM? maybe the ignition itself? ... any ideas before i start throwing money at it?

05 TB EXT 5.3L 4X4

*eventually it always starts..

 

[Tiggerr]

Does putting your foot in the brake help? Or wiggling the shifter? Maybe see if it does it in neutral. Could be nss. Could be solenoid, ignition switch, bad connection at starter or battery, or any of the above switches...bad ground somewhere possible too.

 

[Mooseman]

If it eventually starts and seems to be random, I would suspect the ignition switch. You could download the manuals in my signature and probe the wires coming from the switch for power going to where it's supposed to go. After that, maybe a bad relay or starter? Check to see if power gets to the starter.

 

[kickass audio]

do you happen to have an OBDII scan tool to check for codes? My mom's impala has the exact problem once in a great while and it set check engine codes for fuel system cutoff, multiple BCM communication failures, oil pressure switch failure (this one only comes up when it fails to get the engine to crank, never happens if its working as normal). Her car does have a recall on the ignition switch but is also known for some BCM failures. I agree with what the other guys posted, try to shift your transmission into neutral and have your foot on the brake and try to crank the engine. If it still fails to crank, play with the shifter a little in the neutral position to see if you can get it to crank, if it does then your shift cable may be worn out and could be out of position to where it thinks your not in park.

 

[Five3Blazer]

Thanks a lot guys. Ill try all those suggestions. I do have a obd2 scanner that connects to my laptop so when this happens it does make the check engine light come on. It eventually goes off but ill scan it while its on.

 

[Mounce]

Wouldn't hurt to go ahead and scan it. I think sometimes the PCM will sit on the codes a while before it trips the light but they're still there if you check.

Checked an 04 Tahoe a few days ago just to play with my new scanner. Engine light was off but it had three codes, unsure if they were pending or just stored, though.

I'd try the ignition switch first since it's relatively easy and cheap.

 

[Texan]

Welcome to the Nation.
Can you tell us what codes were set when the CEL came on?

 

[Five3Blazer]

just scanned it, codes: P0335 (crankshaft position sensor A circuit malfunction) and C0700 which it doesnt give a description on my scanner software

 

[Five3Blazer]

i googled the c0700 and cant find a direct explanation. Some say its a bug in the scanner software and doesnt mean anything?

I have a usb OBD2 scanner that connects to my laptop. and EasyOBD2 software. Its always been accurate every other time on about 5 vehicles.

Also after a day or a few once it starts cranking normal, the check engine light goes away until it starts acting up and doesnt start, light comes back.

 

[Mooseman]

Found the C0700 at http://westersgarage.eidnet.ca/OBD2%20Trouble%20Codes.pdf

C0700 Level control accessory inflator switch circuit high

That P0335 could be the source of your troubles. Try changing the sensor. You might need a CASE relearn after but it will run fine without it.

 

[Five3Blazer]

i cleared the codes, c0700 still shows, but it doesnt light up the check engine light.

Ill get the ignition switch tomorrow and start there.

thanks guys!

 

[triz]

i cleared the codes, c0700 still shows, but it doesnt light up the check engine light.

Ill get the ignition switch tomorrow and start there.

thanks guys!

I would hold off on the ignition switch if your getting the code for the crankshaft position sensor. I would replace that instead.

According to what's posted above with the c code. You have airbags on your truck and some type of failure there.

Hold off on changing the switch and replace the crankshaft position sensor. That's more likely the cause of your no start. In fact it's very possible it may start to shut off on you while driving.

 

[Mooseman]

Only stuff affecting the powertrain (P codes) will light the CEL. Airbags, traction/Stabilitrak and 4x4 systems have their own lights. Most other B and C codes don't have a light as they are considered non-essential systems. C0700 has nothing to do with airbags. It's supposed to be for the rear air suspension compressor. As far as I know, Trailblazers never came with them unless they had the accessory inflator as an option. I would ignore this code. Has nothing to do with your problems.

Definitely change the crank sensor before anything else.

 

[Five3Blazer]

This problem has been happening for atleast a year. Wouldn't the sensor finally quit working completely by now?

Ill switch out the crank position sensor today. Hopefully that's all it is!

 

[triz]

Only stuff affecting the powertrain (P codes) will light the CEL. Airbags, traction/Stabilitrak and 4x4 systems have their own lights. Most other B and C codes don't have a light as they are considered non-essential systems. C0700 has nothing to do with airbags. It's supposed to be for the rear air suspension compressor. As far as I know, Trailblazers never came with them unless they had the accessory inflator as an option. I would ignore this code. Has nothing to do with your problems.

Definitely change the crank sensor before anything else.

Apologize for the confusion. I was talking about the rear air suspension and not the "airbags" as in SRS.

 

[Mooseman]

I figured that. Just wanted to be sure that there was no confusion